Science Drivers

The E3SM project is designed to accelerate the development and application of a fully coupled, state-of-the-science Earth system model (ESM) for scientific and energy mission applications. Scientific development of the system will be dictated by three science drivers that broadly cover the foundational science for advancing Earth system prediction. Notably, water cycle, biogeochemistry, and cryosphere systems govern variability and changes in water availability and storms, air and stream temperature, and coastal flooding and sea level rise that are all critical to the energy sector. We pursue three overarching science questions:

(Water Cycle) How do the hydrological cycle interact with the rest of the human-Earth system on local to global scales to determine water availability and water cycle extremes?

(Biogeochemistry) How do the biogeochemical cycle interact with other Earth system components to influence energy-sector decisions?

(Cryosphere Systems) How do rapid changes in cryospheric systems evolve with the Earth system and contribute to sea level rise and increased coastal vulnerability?

These science questions align closely with the Climate and Environmental Science Division’s (CESD) mission objectives to “advance a robust predictive understanding of Earth’s climate and environmental systems and to inform the development of sustainable solutions to the Nation’s energy and environmental challenges.”

Near-term and long-term experiments accompanies the overarching question of each science driver. These experiments represent simulation targets for v1 and v2 of the E3SM system during the first 4 – 6 years of the project and for v3 and v4 in the 10-year horizon. The v1 and v2 experimental campaigns are designed to “stretch” goals for the initial round of E3SM development and preparatory steps toward a grand challenge objective suitable for the extreme-scale computing resources anticipated for 2020 and beyond. The v3/v4 campaign is designed to revolutionize the predictions connected with each driver and utilize the full power of the Exascale systems leveraged with transformative advances in model physics, numerical formulation, analytics, and computational implementation.

Consistent with the three science drivers and associated overarching science questions, the science questions motivating the near-term, medium-term, and long-term model development and experiments are listed in the table below. Progressing through four versions of E3SM, the science questions will be addressed by optimizing the use of higher resolution, increasing complexity, and larger ensemble size with our exascale computational strategy (Section 1.4) to improve predictions of future changes in water cycle, biogeochemistry, and cryosphere systems that challenge energy production and use.